Transparent Electrodes And Interfacial Engineering Of Indium-free Polymer Solar Cells

Polymer solar cells?PSCs?have attracted the attention of researchers due to their portability,flexional characteristic and easy processing.In general,PSCs are mainly prepared using transparent conducting indium tin oxide?ITO?film as an electrode.In view of sizable cost,intrinsic brittleness as well as contact defects between the electrode and the interface layer,the further development of PSCs is restricted.In order to deep research scientific problems between the electrode and the interface layer,relative research has been gradually implemented from the electrode and the interface layer,obtaining inexpensive and stable ITO-free PSCs with high efficiency.In this paper,the authors explore through two sections.Firstly,aiming at the existence of poor conductivity and unmatched energy level in traditional zinc oxide film as an electron transport layer?ZnO ETL?,highly dispersed graphene sheets?graphene:ethyl cellulose?G:EC??with high conductivity were prepared by physical method,and ZnO nanocrystals could be in situ formed in the graphene matrix,producing a new ETL?ZnO@G:EC?1 v%??.Introducing 1% volume of G:EC ethanol solution in ZnO precursor solution,the ZnO@G:EC?1 v%?ETL displays smoother morphology,higher conductivity and matched energy level than the bare ZnO ETL.Therefore,the power conversion efficiency?PCE?of each device is obviously improved employing the new ETL in devices based on P3HT:PC61BM or PTB7:PC71BM as an active layer.Secondly,in view of disadvantages of the ITO electrode,a cheap and solution processable transparent electrode with high conductivity should be designed and prepared.Poly?3,4-ethylenedioxythiophene?:polystyrene sulfonate?PEDOT:PSS?as a raw material was pre-treated with a polyethylene glycol 4000?PEG4000?additive,and then its film was further post-treated with sulfuric acid?H₂SO₄?,achieving a large-area indium-free transparent S-PEDOT:PSS:PEG4000?6.5%?electrode for PSCs.The conductivity of S-PEDOT:PSS:PEG4000?6.5%?film is distinctly enhanced up to 4027.4 S cm-1,and its work function is adjusted.According to related characterization of photoelectronic properties and the performance of various devices,the S-PEDOT:PSS:PEG4000?6.5%?film is a good cathode.The performance of the device is related to the conductivity of the material,at the same time,because of excellent electrical properties,relatively inexpensive price and solution preparation of the new ETL and cathode,this device based on these new materials has more advantages than the device with the same structure with ITO and has an extensively commercial application prospect.